Wireless Wide Area Networks (WWANs, better known as cellular service providers) allow computers to connect to networks employing WWAN protocols such as Global System Mobile (GSM), General Packet Radio Service (GPRS), Code Division Multiple Access (CDMA), etc. Although originally used for voice transmission, these networks can provide efficient data services to their end users, who have computers or other devices equipped with WWAN network interface hardware.
In order to connect to a network, operators generally require some method of identification and authentication to ensure that a user is entitled to gain access to the network and that the user's identity is not being misappropriated. To this end, prior GSM/GPRS systems required users to subscribe to network services by registering with the network operator and physically receiving a Subscriber Identity Module (SIM), which is used by the user's networking device. The SIM is a single-chip computer containing memory, a microprocessor and with or without an operating system, a file system, and applications. It is a security module for customer authentication, owned (and trusted) by the GSM/GPRS network operator. The card is about the size of a thumbprint. It stores unique identifying credentials, including a master key, that allow the network operator to verify the authenticity of the user's identity. The master key is a fixed value uniquely associated with the SIM card. SIM cards also sometimes contain an integrated web browser, a roaming profile, games and entertainment, and other personal information such as an address book and text messages.
A user wishing to subscribe to a GPRS carrier in a previous system contacted an agent of the carrier through some direct human contact (over the telephone, at a customer care center of the carrier, etc.) and, after some interaction, obtained a SIM card that had been associated with that user's identity. The subscription process was thus very much an off-line process. The SIM card was inserted into the networking device, and the user could then access that particular carrier's network. Once obtained, the SIM card could be subsequently provisioned with data, such as applications, menus, network information, etc., from the network operator using an over-the-air (OTA) provisioning protocol. The master key on the SIM card, however, is fixed.